Injection of rabbits with human cells infected with human immunodeficiency virus I (HIV-1) has lead to seroconversion within six weeks and virus has been cultured from peripheral blood lymphocytes (PBL) from the injected animals. The use of rabbits for HIV-1 infection was prompted by our recent finding that rabbit T cell and macrophage lines infection in vitro with HIV produced reverse transcriptase, RNA viral transcripts and were positive for viral proteins, by immunofluorescence and by Western blots using AIDS patient sera. Evidence for in vivo infection was seen in rabbits that had been previously seroconverted with the virus HTLV- 1 as well as in animals with no history of HTLV-1 infection. Sporadic signs of illness were seen in infected animals by gross observation and by chemical and hematologic analyses. Examination of organs from necropsy of single or doubly infected animals showed splenic enlargement with hyperplasia evident upon histologic examination which also revealed that lungs were infiltrated with lymphocytes. This animal model for HIV infection may be useful for testing vaccines and theraputic drugs, for determining modes of HIV viral transmission and for following the natural course of HIV-1 infection in an experimental animal.